I'm going to try to make this short so its not boring to read. I got a good deal on this motor and I've wanted a good built motor to play with. This motor came out of a 79 ford truck a guy years ago ran on the drag strip here where I live. The strip was shut down and the motor pulled and stored away but was stored right. The motor is a .030 over 302 (D20E-6015-AB) Its a 1972 model motor and the heads are (D2OE) which is 72 model also. The heads have 302 with number 69 underneath, dont know what the 69 means. Anyway the guys said its was 13:1 compression and if it is I want to drop this down so it would be more street friendly. I pulled the heads and it does have the high compression pistons in it. They are marked TRW .030 and the part number is L2249N. I'll post the cam spec's when I pull it out so I can get the number off it. The valve size I dont know yet either, I havent got that far yet. When I get those numbers for you guys I just want some help on getting the compression down. I'm hoping its not 13:1 like the guy said. I want to get it around 11:1 and I guess it could be that, like I said I'm going on what the guy told me. Will the cam numbers help on what it could have been. The guy was guessing the came was around a .590 lift. One head is still on could I do a compression check on the one side and get a idea of what it was. I'd like to start a build post here and I want plenty of help from you guys. I'll get those numbers for you guys and we can go from there. Thanks Scott

 

High compression with a radical cam will result in a lower dynamic compression ratio, allowing the engine to run without detonation. That's the theory. So find out what the cam is. If you want the static CR, you need the cylinder head volume, any valve relief volume, head gasket thickness, bore etc. Like so:

Engine Compression Ratio (CR) Calculator

 

85e150six4mtod, Thanks for the help. I'm going to get the cam number today and call comp and see if they can help me find out what it is. The guy that had the motor he was talking about the dynamic and static CR to. I have built stock motors for myself before and always wanted to do a motor like this. So with this motor I'm trying to find out what I have so I can know where to start. I've never worried about compression or head gasket thickness before because of the stock build I have done. So this is all new to me how you figure this out. I'm reading everything I can so I can figure this stuff out, I'm looking forward to doing this. I will get as much info today as I can and post it back here and maybe you can help me to on this. Thanks for getting back with me. Scott

 

Alright this is what I found out today.
Cam: Engle Camshaft, 236 @ .050, 523 Lift, 282 Duration, 109 Lobe Center, operating range is 2000-6500 RPM.
Pistons: TRW Part# L2249N .030 overbore high compression pistons
Heads: Stock cast iron, 64cc
I miked the valves and this is what I got if I done it right. Valve size is 1.78 and 1.46
Head gasket thickness is .054
What I figured up is with a 64cc head the motor is 12:1 compression, and if I want to get it down to 10:1 then I need to get a 72cc or 74cc head. I dont want to have to put racing fuel in it all the time. I dont care to run 93 because I only go to the car shows around close to the house. I dont know much about a high compression motor but if 12:1 isnt to bad to have for what I want to do then I'll use the heads I have. The reason for that is because they have the valve springs in them for the cam. I know I can change those out to another set of heads if I have to. I do have a set of 79 model 302 heads that might bring the compression down some and I have a set of 91 heads also. Any help at all or if you guys need somemore info let me know. Let me know if you all think this would be a good motor for what I want to do. Drive to the car shows and cruising around on the weekends. Thanks Scott

 

First thing you have to know is D2OE 302 heads have 58cc combustion chambers so unless they have been worked over to enlarge the chambers your CR calcs are off, but it also depends upon the pistons.. are they flat tops or domed even?

 

They are dome pistons. With that 58cc I would be in the 13:1 compression range. The pistons are TRW L2249N. The guy I got the motor from said I would need to get a 72cc or 74cc head to get the compression down to 10:1. I'll get the numbers off the 79 heads for you, that would be great if they would work. I have a set of E6AE heads also, I believe these are 86 model heads. Do you know what cc's these would be. Thanks Scott

 

Ok, I've done more figures on the CR on my motor. Originaly the PO said it was 13:1 but its not. The best I can figure out it is 12:1 which is still high. So that why I cant use the DOOE heads on this motor. I bought a set of E7 heads which has a 62-62cc so that will bring my CR down to 10:1. I'm waiting on my motor and heads to come back from the machine shop. I took them there to get cleaned and check. I'm hoping to get them today so I can start on it again. My crank and cam checked out fine so I'm going to use them. With the E7 heads I'm going to have to check my pushrod size because of the pedestal mounted rockers. I got a pushrod checker from comp so I can get it right. Just wanted to let you guys know where I was on the build. Scott